Rigid micro-modules with iLED and light conductor

ABSTRACT

A light-emitting module structure comprises a support substrate and a micro-module disposed on or in the support substrate that extends over only a portion of the support substrate. The micro-module comprises a rigid module substrate, an inorganic light-emitting diode, a power source, and a control circuit. The inorganic light-emitting diode, the power source, and the control circuit are disposed on or in the module substrate and the control circuit receives power from the power source to control the inorganic light-emitting diode to emit light. A light conductor is disposed on or in the support substrate and in alignment with the micro-module so that the inorganic light-emitting diode is disposed to emit light into the light conductor and the light conductor conducts the light beyond the micro-module to emit the light from the light conductor.

PRIORITY APPLICATION

This application claims the benefit of U.S. Provisional PatentApplication No. 62/585,441, filed on Nov. 13, 2017, entitled RigidMicro-Modules with ILED and Light Conductor, the disclosure of which isincorporated by reference herein in its entirety.

CROSS REFERENCE TO RELATED APPLICATIONS

Reference is made to U.S. patent application Ser. No. 15/433,119, filedFeb. 15, 2017, entitled “Hybrid Banknote with Electronic Indicia”, U.S.patent application Ser. No. 15/157,838, filed May 18, 2016, entitledHybrid Banknote with Electronic Indicia Using Near-Field Communications,U.S. patent application Ser. No. 15/452,183, filed Mar. 7, 2017,entitled Wirelessly Powered Display and System, and U.S. patentapplication Ser. No. 15/678,981, filed Aug. 16, 2017, entitled HybridBanknote with Electronic Indicia Using Near-Field Communications, thecontents of each of which are hereby incorporated by reference in theirentirety.

TECHNICAL FIELD

The present disclosure relates generally to micro-modules capable ofemitting light [e.g., for use with documents such as security or valuedocuments (e.g., banknotes)] and particularly, in some embodiments, toflexible documents having one or more micro-modules comprisingelectronically controlled inorganic light-emitting diodes powered bypiezo-electric elements disposed thereon.

BACKGROUND

Monetary instruments issued by governments such as money or currency areused throughout the world today. Government-issued currency typicallyincludes banknotes (also known as paper currency or bills) havingvisible markings printed on high-quality paper, plastic, or paperimpregnated or protected with other materials, such as plastic. Thevisible markings indicate the denomination (monetary value) of thebanknote, include a serial number, and incorporate decorations such asimages, and anti-counterfeiting structures such as special threads,ribbons, and holograms. Currency circulates within an economic system asa medium of monetary exchange having a fixed value until it isphysically worn out. Worn out banknotes are generally returned by banksor other financial institutions and then replaced.

Other privately issued monetary instruments are also used, such ascredit cards and gift cards. These cards typically include anelectronically accessible value (e.g., stored in a magnetic stripe or ina chip in the card) or indicate an electronically accessible accountthat can be used to make purchases. However, the value of the card isnot readily viewed by a user without special equipment, such as areader.

In the past, banknotes have not been electronically enabled. However,more recently there have been proposals to use RFID (radio-frequencyidentification device) in banknotes to validate the banknote and avoidcounterfeiting. For example, U.S. Pat. Nos. 8,391,688 and 8,791,822disclose systems for currency validation. U.S. Pat. No. 5,394,969describes a capacitance-based verification device for a security threadembedded within currency paper to defeat counterfeiting. Securitysystems for scanning a paper banknote and checking identificationinformation in the banknote (e.g., the serial number) with anetwork-accessible database have been proposed, for example in U.S. Pat.No. 6,131,718. In all of these systems, however, there is no way tovisibly test small details of a banknote without using a separateelectronic or optical reader.

Security documents, such as government-issued identification documents,for example passports and driver's licenses are also widely used. Inrecent years, such documents have incorporated electronic devices.However, these documents are typically not subjected to the same degreeof environmental and mechanical stress and abuse that banknotesexperience.

There remains a need therefore, for value and security documents such asbanknotes with electronically controlled, visible indicia that preventcounterfeiting and are accessible (e.g., observable) without using aseparate electronic or optical reader.

SUMMARY

Certain embodiments provide a light-emitting module structure thatcomprises a support substrate and a micro-module disposed on or in thesupport substrate that extends over only a portion of the supportsubstrate. The micro-module comprises a rigid module substrate, aninorganic light-emitting diode, a power source, and a control circuit.The inorganic light-emitting diode, the power source, and the controlcircuit are disposed on or in the module substrate and the controlcircuit receives power from the power source to control the inorganiclight-emitting diode to emit light. A light conductor is disposed on orin the support substrate and in alignment with the micro-module so thatthe inorganic light-emitting diode is disposed to emit light into thelight conductor and the light conductor conducts and transmits the lightbeyond the micro-module to emit the light from the light conductor. Themicro-module can comprise an electrical interconnection circuit thatelectrically interconnects the power source, the control circuit, andthe inorganic light-emitting diode.

In some embodiments, the module substrate is a semiconductor substrateand the control circuit is formed at least partially in or on the modulesubstrate. In some embodiments, the control circuit can be amicro-transfer printed integrated circuit having a circuit substrateseparate (e.g., distinct and independent) from the module substrate andsupport substrate and at least a portion of a fractured or separatedtether. The inorganic light-emitting diode can be a micro-transferprinted inorganic light-emitting diode (iLED) having an iLED substrateseparate (e.g., distinct and independent) from the module and supportsubstrates and at least a portion of a fractured or separated tether.Similarly, the power source can be a micro-transfer printed power sourcehaving a power source substrate separate (e.g., distinct andindependent) from the module and support substrates and at least aportion of a fractured or separated tether. Any one or all of theinorganic light-emitting diode, the power source, and the controlcircuit can be micro-transfer printed on the module substrate.

In certain embodiments, the power source comprises a solar cellresponsive to light, a piezo-electric structure responsive to mechanicalpressure, or an antenna responsive to electromagnetic radiation such asradio waves. The piezo-electric structure can comprise a stack ofpiezo-electric elements electrically connected in serial.

In certain embodiments, the light conductor comprises one or morereflectors and a transparent layer adjacent to the reflector in adirection orthogonal to the support substrate or disposed between tworeflectors. A reflector can be disposed on the support substrate betweenthe support substrate and the micro-module, a reflector can be disposedon the support substrate so that the support substrate is between thereflector and the micro-module, or the micro-module can be disposedbetween the support substrate and a reflector. In some embodiments, thelight conductor comprises one or more light pipes, one or morediffusers, light leaks, or one or more optical gaps disposed at least inpart beyond the micro-module. The light conductor can extend over only aportion of the support substrate providing optical gaps at the extremityof the light conductor. Optical gaps are locations in the lightconductor where light can be emitted from the light conductor, forexample openings in a reflector where no reflective material is present.

In some embodiments, the inorganic light-emitting diode primarily emitslight through the module substrate, the inorganic light-emitting diodeprimarily emits light in a direction away from the module substrate, theinorganic light-emitting diode is disposed between the module substrateand the support substrate, or the module substrate is disposed betweenthe inorganic light-emitting diode and the support substrate.

In certain embodiments, the support substrate is flexible. In someembodiments, the support substrate is a security strip, that can bedisposed on or in a security or value document such as a banknote, forexample by lamination or weaving. In some embodiments, the supportsubstrate is a banknote, a security document, or value document, aportion of a security or value document, or a layer on or in a securityor value document.

Certain embodiments provide anti-counterfeiting features in value orsecurity documents such as banknotes that can be visibly ascertainedwithout requiring specialized equipment and that are robust in thepresence of environmental and mechanical stress. The features can berobust to physical abuse because the electronic portion of the featureis provided on a very small, relatively rigid module substrate and theoptical portion of the feature is relatively flexible.

In some embodiments, a piezo-electric power source comprises a stack ofpiezo-electric elements electrically connected in serial. The stack ofpiezo-electric elements is responsive to mechanical pressure to produceelectrical power. An electrical conductor can be disposed in the stackbetween at least two of the piezo-electric elements.

The piezo-electric elements can be less than or equal to 500 micronsthick, 200 microns thick, 100 microns thick, 50 microns thick, 20microns thick, 10 microns thick, or 5 microns thick and the stack ofpiezo-electric elements can be greater than or equal to 100 micronsthick, 500 microns thick, one mm thick, two mm thick, four mm thick,five mm thick, or 10 mm thick. The stack of piezo-electric elements cancomprise two, three, four, five, ten, twenty, fifty, or one hundredpiezo-electric elements. The stack of piezo-electric elements can havean area in a plane orthogonal to the element stack of less than or equalto 100 square mm, 25 square mm, one square mm, 250,000 square microns,40,000 square microns, 10,000 square microns, 2,500 square microns,1,000 square microns, 500 square microns, or 100 square microns. In someembodiments, the piezo-electric power source comprises a supportsubstrate or a module substrate and the piezo-electric stack is disposedon the support substrate or the module substrate. The support substratecan be flexible.

A plurality of stacks of piezo-electric elements can be electricallyconnected serially or in parallel and disposed on a substrate, such as asupport or module substrate. Each stack of the plurality of stacks ofpiezo-electric elements can be spatially separated from every otherstack of piezo-electric elements.

In certain embodiments, one or more of the piezo-electric elements is apiezo-electric capacitor. In certain embodiments, a control circuit iselectrically connected to the piezo-electric stack for storing theelectrical power so that the control circuit stores at least a portionof the electrical power. The control circuit can be electricallyconnected to the piezo-electric stack for converting the electricalpower from one voltage, current, or temporal duration to anotherdifferent voltage, current, or temporal duration.

In certain embodiments, a temporal duration for applying mechanicalpressure to the piezo-electric stack is a press duration, and thecontrol circuit outputs energy for a temporal output duration. Theoutput duration can be temporally delayed from the press duration by atleast one msec, the output duration can be less than the press duration,the output duration can be greater than the press duration, or theoutput duration can be greater than or equal to one msec, or anycombination of output, temporal, and press durations.

Methods of making a piezo-electric power source comprise providing apower-source substrate and one or more element wafers. The power-sourcesubstrate can be a module substrate or a power-source wafer. Eachelement wafer comprises one or more piezo-electric elements; eachpiezo-electric element is disposed over a sacrificial portion separatedby anchor portions of the element wafer. One or more piezo-electricelements are released and micro-transfer printed from the one or moreelement wafers onto or over a piezo-electric element onto thepower-source substrate or module substrate to form a stack ofpiezo-electric elements. In one embodiment, a stack on the power-sourcesubstrate can be transferred to the module substrate. In someembodiments, the stack can be disposed over a sacrificial portionseparated by anchor portions of the power-source wafer, released fromthe power-source wafer, and micro-transfer printed to the modulesubstrate.

An electrical conductor can be provided between the piezo-electricelements and the electrical conductor can be heated and cooled to adherethe stacked piezo-electric elements to each other. The electricalconductor can be an electrically conductive interface between twopiezo-electric elements in the stack.

Certain embodiments provide a method of operating a piezo-electricdevice for converting mechanical pressure into electrical power. Apiezo-electric power source comprising a control circuit electricallyconnected to the piezo-electric power source and an output deviceelectrically connected and responsive to the control circuit to outputenergy are provided. A temporal duration for applying mechanicalpressure to the piezo-electric stack is a press duration, the controlcircuit controls the output device to output energy for a temporaloutput duration, and the output duration is temporally delayed from thepress duration by at least one msec.

An observer has a pressing device (such as a finger) and disposes thepressing device on or over the piezo-electric power source to obscurethe piezo-electric power source and iLED. The piezo-electric powersource is pressed with the pressing device and the pressing device isremoved so that the piezo-electric power source is visible. The observerwaits for a temporal delay equal to or greater than one tenth of asecond, one quarter of a second, one half of a second, or one second,for example, and then observes light output from the output device afterthe temporal delay. The light output can vary, for example blink or varyin luminance.

Certain embodiments provide a piezo-electric structure usingmicro-transfer printing methods that can provide increased power whenpressed with a pressing device. The increased power can be provided,through a control circuit, to an iLED so that the iLED emits light. TheiLED is obscured by the pressing device and light output from the iLEDis delayed until the pressing device is removed from the piezo-electricstructure.

Certain embodiments provide a piezo-electric structure usingmicro-transfer printing methods that can provide increased power to anILED and visibility to the light output from the iLED. Thepiezo-electric structure can be small or include small piezo-electricelements that facilitate integration on a small substrate.

In certain embodiments, a method of disposing one or more micro-moduleson or in a support substrate to provide a light-emitting modulestructure comprises providing a micro-module source wafer comprising oneor more individual (e.g., separate and independent) micro-modules. Eachmicro-module comprises a relatively rigid module substrate (compared tothe support substrate), an inorganic light-emitting diode, a powersource, and a control circuit. The inorganic light-emitting diode, powersource, and control circuit are disposed on or in the module substrateand the control circuit receives power from the power source to controlthe inorganic light-emitting diode to emit light using electricalconnections provided on the module substrate. If the support substratecomprises a light conductor, one or more of the micro-modules aredisposed onto the support substrate. Otherwise one or more of themicro-modules are disposed onto the support substrate and a lightconductor is disposed on the support substrate or the micro-module. Thelight conductor is disposed in alignment with the inorganiclight-emitting diode so that the inorganic light-emitting diode emitslight into the light conductor and the light conductor conducts thelight beyond the micro-module to emit the light from a light-emittinglocation of the light-emitting module structure.

In certain embodiments, the micro-module source wafer can comprise oneor more sacrificial portions. Each sacrificial portion can be disposedbetween anchor portions of the micro-module source wafer and eachmicro-module can be disposed completely over a sacrificial portion. Oneor more of the micro-modules are disposed onto the support substrate bymicro-transfer printing one or more micro-modules from the micro-modulesource wafer to the support substrate and can comprise a portion of atether, for example a broken, fractured, or separated tether.

One or more inorganic light-emitting diode (iLED) source wafers can alsobe provided, each comprising one or more sacrificial portions, eachsacrificial portion disposed between anchor portions of the iLED sourcewafer, and each iLED is disposed completely over a sacrificial portion.In certain embodiments, methods comprise disposing one or more of theiLEDs onto the module substrate by micro-transfer printing one or moreiLEDs from the iLED source wafer to the module substrate so that theiLED comprises a broken, fractured, or separated tether. Similarly, thecontrol circuit or power source can be provided on respective sourcewafers and micro-transfer printed onto a module substrate together witha portion of a tether, for example a broken, fractured, or separatedtether.

The support substrate can be a security or value document, a portion ofa security or value document, or a layer on or in a security or valuedocument. In certain embodiments, methods comprise disposing the supportsubstrate onto or into a document substrate that is a security or valuedocument, a portion of a security or value document, or a layer on or ina security or value document. In some embodiments, a method compriseslaminating the support substrate to the document substrate, adhering themicro-module to the document substrate and removing the supportsubstrate. A sealing or encapsulation layer can be provided over themicro-module on the document substrate to protect the micro-module.

Methods in accordance with some embodiments comprise a polymer carriersubstrate and comprise disposing the micro-module on the polymer carrierand disposing the polymer carrier on the support substrate. Methods cancomprise adhering the micro-module to the support substrate and removingthe polymer carrier, providing a sealing or encapsulation layer over themicro-module, or providing a sealing or encapsulation layer over thesupport substrate and the micro-module.

According to methods in accordance with some embodiments, the powersource is a piezo-electric power source, comprising a plurality ofpiezo-electric elements. Methods can comprise disposing one or morepiezo-electric elements onto or over a piezo-electric element to form astack of piezo-electric elements, disposing each of the one or morepiezo-electric elements onto or over the module substrate andelectrically connecting the piezo-electric elements, or micro-transferprinting one or more piezo-electric elements from a piezo-electricelement source wafer onto the piezo-electric element.

The piezo-electric element can be disposed on the module substrate, forexample by micro-transfer printing a piezo-electric element from apiezo-electric element source wafer onto the module substrate. In someembodiments, a method comprises forming a piezo-electric power source onthe module substrate using photolithographic methods and materials. Somemethods comprise disposing each of one or more electrical conductorsover a piezo-electric element and disposing another piezo-electricelement onto or over each electrical conductor and heating theelectrical conductor and cooling the electrical conductor to adhere thepiezo-electric element to the other piezo-electric element. All of theelectrical conductors can be heated and cooled in a common step at thesame time.

In some aspects, the present disclosure provides a light-emitting modulestructure, comprising: a support substrate; a micro-module disposed onor in the support substrate and extending over only a portion of thesupport substrate, the micro-module comprising a rigid module substrate,an inorganic light-emitting diode, a power source, and a controlcircuit, wherein the inorganic light-emitting diode, the power source,and the control circuit are each disposed on or in the module substrateand the control circuit, the power source, and the inorganiclight-emitting diode are electrically connected such that the controlcircuit receives power from the power source to control the inorganiclight-emitting diode to emit light; a light conductor disposed on or inthe support substrate and in alignment with the micro-module such thatthe inorganic light-emitting diode is disposed to emit light into thelight conductor and the light conductor conducts the light beyond themicro-module to emit the light from the light conductor.

In certain embodiments, the module substrate is a semiconductorsubstrate and the control circuit is formed at least partially in themodule substrate.

In certain embodiments, at least one of (i) the control circuit is amicro-transfer printed integrated circuit comprising a circuit substrateseparate (e.g., distinct and independent) from the module substrate andthe support substrate and at least a portion of a fractured or separatedtether, (ii) the inorganic light-emitting diode is a micro-transferprinted inorganic light-emitting diode (iLED) comprising an iLEDsubstrate separate (e.g., distinct and independent) from the modulesubstrate and the support substrate and at least a portion of afractured or separated tether, and (iii) the power source is amicro-transfer printed power source comprising a power source substrateseparate (e.g., distinct and independent) from the module and supportsubstrates and at least a portion of a fractured or separated tether.

In certain embodiments, the power source comprises a solar cell, apiezo-electric structure, or an antenna. In certain embodiments, thepower source comprises a stack of piezo-electric elements, wherein thepiezo-electric elements of the stack are electrically connected inserial.

In certain embodiments, the micro-module comprises an electricalinterconnection circuit that electrically interconnects the powersource, the control circuit, and the inorganic light-emitting diode.

In certain embodiments, the light conductor comprises a reflector and atransparent layer, wherein the transparent layer is disposed adjacent tothe reflector in a direction orthogonal to the support substrate. Incertain embodiments, the light conductor comprises two reflectors andthe transparent layer is disposed between two reflectors (e.g., whereinthe transparent layer is or comprises the support substrate). In certainembodiments, the light conductor comprises a reflector and (i) thereflector is disposed on the support substrate between the supportsubstrate and the micro-module, (ii) the reflector is disposed on thesupport substrate so that the support substrate is between the reflectorand the micro-module, or (iii) the micro-module is disposed between thesupport substrate and the reflector. In certain embodiments, the lightconductor comprises one or more light pipes. In certain embodiments, thelight conductor comprises at least one of one or more diffusers, one ormore light leaks, and one or more optical gaps disposed beyond themicro-module. In certain embodiments, the light conductor extends overonly a portion of the support substrate providing optical gaps at theextremity of the light conductor.

In certain embodiments, the inorganic light-emitting diode is disposedsuch that the inorganic light-emitting diode emits light through themodule substrate [e.g., primarily through the module substrate (i.e.,such that a majority of light emitted from the inorganic light-emittingdiode is emitted through the module substrate)]. In certain embodiments,the inorganic light-emitting diode primarily emits light in a directionaway from the module substrate. In certain embodiments, the inorganiclight-emitting diode is disposed between the module substrate and thesupport substrate. In certain embodiments, the module substrate isdisposed between the inorganic light-emitting diode and the supportsubstrate.

In certain embodiments, the support substrate is flexible. In certainembodiments, the support substrate is a security strip. In certainembodiments, the light-emitting module structure comprises a security orvalue document, wherein the security strip is disposed on or in thesecurity or value document. In certain embodiments, the supportsubstrate is at least a portion of a security or value document (e.g.,is a security or value document) or a layer on or in a security or valuedocument.

In some aspects, the present disclosure provides a piezo-electric powersource, comprising a stack of piezo-electric elements that areelectrically connected in serial, wherein the piezo-electric elements ofthe stack are responsive to mechanical pressure to produce electricalpower.

In certain embodiments, the piezo-electric power source comprises anelectrical conductor disposed in the stack between at least two of thepiezo-electric elements.

In certain embodiments, the piezo-electric elements are no more than 500microns thick (e.g., no more than 200 microns thick, no more than 100microns thick, no more than 50 microns thick, no more than 20 micronsthick, no more than 10 microns thick, or no more than 5 microns thick).In certain embodiments, the stack of piezo-electric elements has athickness of at least 100 microns (e.g., at least 500 microns, at leastone mm, at least two mm, at least four mm, at least five mm, or at least10 mm). In certain embodiments, the stack of piezo-electric elementscomprises two, three, four, five, ten, twenty, fifty, or one hundredpiezo-electric elements.

In certain embodiments, the stack of piezo-electric elements comprisesat least three (e.g., at least four, at least five, at least ten, atleast twenty, at least fifty, or at least one hundred piezo-electricelements). In certain embodiments, the stack has an area in a planeorthogonal to the stack of piezo-electric elements (e.g., a stackingdirection of the stack) of no more than 100 mm² (e.g., no more than 25mm², no more than one mm², no more than 250,000 μm², no more than 40,000μm², no more than 10,000 μm², no more than 2,500 μm², no more than 1,000μm², no more than 500 μm², or no more than 100 μm²).

In certain embodiments, the piezo-electric power source comprises aplurality of stacks of piezo-electric elements, wherein the stacks ofpiezo-electric elements in the plurality of stacks of piezo-electricelements are electrically connected in parallel. In certain embodiments,the piezo-electric power source comprises a plurality of stacks ofpiezo-electric elements (e.g., wherein the stacks in the plurality ofstacks are electrically connected in parallel) wherein each stack of theplurality of stacks of piezo-electric elements is spatially separatedfrom every other stack of piezo-electric elements. In certainembodiments, the piezo-electric power source comprises a plurality ofstacks of piezo-electric elements, wherein the stacks of piezo-electricelements in the plurality of stacks of piezo-electric elements areelectrically connected in parallel and each stack of the plurality ofstacks of piezo-electric elements is spatially separated from everyother stacks of piezo-electric elements.

In certain embodiments, one or more of the piezo-electric elements ofthe stack of piezo-electric elements is a piezo-electric capacitor.

In certain embodiments, the piezo-electric power source comprises acontrol circuit, electrically connected to the stack of piezo-electricelements, for storing at least a portion of the electrical power. Incertain embodiments, the piezo-electric power source comprises a controlcircuit, electrically connected to the stack of piezo-electric elements,for converting the electrical power from one voltage to another voltage,from one current to another current, or from one temporal duration toanother temporal duration. In certain embodiments, the control circuitis for converting the electrical power from one temporal duration toanother temporal duration and the control circuit is adapted to converta press duration that is a temporal duration that mechanical pressure isapplied to the stack of piezo-electric elements to an output durationduring which energy is output. In certain embodiments, the controlcircuit controls the output duration to be temporally delayed from thepress duration by at least one msec. In certain embodiments, the outputduration is less than the press duration. In certain embodiments, theoutput duration is greater than the press duration. In certainembodiments, the output duration is greater than or equal to one msec.

In certain embodiments, the piezo-electric power source comprises asupport substrate and the stack of piezo-electric elements is disposedon the support substrate, or the piezo-electric power source comprises amodule substrate, and the stack of piezo-electric elements is disposedon the module substrate.

In some aspects, the present disclosure provides A method of making apiezo-electric power source, comprising: providing a power-sourcesubstrate; providing one or more element wafers, each of the one or moreelement wafers comprising one or more piezo-electric elements, each ofthe one or more piezo-electric element disposed over a sacrificialportion of the element wafer separated by anchor portions of the elementwafer; and releasing and transferring (e.g., micro-transfer printing)one or more piezo-electric elements from the one or more element wafersonto or over a piezo-electric element on the power-source substrate(e.g., after releasing and micro-transfer printing one or morepiezo-electric elements from the one or more element wafers onto or overthe power-source substrate)(e.g., thereby forming one or more stacks ofpiezo-electric elements). In certain embodiments, the method comprisesproviding an electrical conductor between the piezo-electric elements;and optionally, heating or cooling the electrical conductor to adherepiezo-electric elements in a stack to each other.

In some aspects, the present disclosure provides a piezo-electricdevice, comprising: a piezo-electric power source for convertingmechanical pressure into electrical power; a control circuitelectrically connected to the piezo-electric power source; an outputdevice electrically connected and responsive to the control circuit tooutput energy, wherein the control circuit controls the output device tooutput energy for a temporal output duration and the temporal outputduration is temporally delayed from a press duration by a temporal delayof at least one msec (e.g., and no more than one minute), wherein thepress duration is a duration during which mechanical pressure is appliedto the piezo-electric power source (e.g., a stack of piezo-electricelements in the piezo-electric power source).

In certain embodiments, the temporal output duration is less than thepress duration. In certain embodiments, the temporal output duration isgreater than the press duration. In certain embodiments, the temporaloutput duration is greater than or equal to one msec.

In certain embodiments, the control circuit is for converting theelectrical power from one voltage to another voltage, from one currentto another current, or from one temporal duration to another temporalduration.

In certain embodiments, the piezo-electric device comprises a stack ofpiezo-electric elements responsive to mechanical pressure to produceelectrical power, wherein the piezo-electric elements in the stack ofpiezo-electric elements are electrically connected in serial (e.g.,wherein the piezo-electric power source comprises the stack ofpiezo-electric elements).

In certain embodiments, the piezo-electric device comprises anelectrical conductor disposed in the stack between at least twopiezo-electric elements.

In certain embodiments, the piezo-electric elements are no more than 500microns thick (e.g., no more than 200 microns thick, no more than 100microns thick, no more than 50 microns thick, no more than 20 micronsthick, no more than 10 microns thick, or no more than five micronsthick). In certain embodiments, the stack of piezo-electric elements noless than one mm thick (e.g., no less than two mm thick, no less thanfour mm thick, no less than five mm thick, or no less than 10 mm thick).In certain embodiments, the stack of piezo-electric elements comprisestwo, three, four, five, ten, twenty, fifty, or one hundredpiezo-electric elements. In certain embodiments, the stack ofpiezo-electric elements comprises at least three (e.g., at least four,at least five, at least ten, at least twenty, at least fifty, or atleast one hundred piezo-electric elements). In certain embodiments, thestack has an area in a plane orthogonal to the stack of piezo-electricelements (e.g., a stacking direction of the stack) of no more than 100mm² (e.g., no more than 25 mm², no more than one mm², no more than250,000 μm², no more than 40,000 μm², no more than 10,000 μm², no morethan 2,500 μm², no more than 1,000 μm², no more than 500 μm², or no morethan 100 μm²).

In certain embodiments, the piezo-electric device comprises a pluralityof stacks of piezo-electric elements, wherein the stacks ofpiezo-electric elements in the plurality of stacks of piezo-electricelements are electrically connected in parallel. In certain embodiments,each stack of the plurality of stacks of piezo-electric elements isspatially separated from every other stack of piezo-electric elements.In certain embodiments, one or more of the piezo-electric elements ofthe stack of piezo-electric elements is a piezo-electric capacitor.

In certain embodiments, the control circuit comprises circuitry forstoring at least a portion of the electrical power.

In certain embodiments, the piezo-electric device comprises a supportsubstrate and wherein the piezo-electric power source is disposed on thesupport substrate. In certain embodiments, the support substrate isflexible.

In certain embodiments, the piezo-electric device comprises a pluralityof stacks of piezo-electric elements, wherein the stacks in theplurality of stacks of piezo-electric elements are electricallyconnected in serial and each stack of the plurality of stacks ofpiezo-electric elements is spatially separated from every other stack ofpiezo-electric elements.

In some aspects, the present disclosure provides a method of operating apiezo-electric device for converting mechanical pressure into electricalpower, comprising: providing the piezo-electric device (e.g., disposedon a security or value document), wherein the piezo-electric devicecomprises: a piezo-electric power source, a control circuit electricallyconnected to the piezo-electric power source, and an output deviceelectrically connected and responsive to the control circuit to outputenergy, wherein the control circuit controls the output device to outputenergy for a temporal output duration and the output duration istemporally delayed from the press duration by at least one msec, whereinthe press duration is a duration during which mechanical pressure isapplied to the piezo-electric power source (e.g., a stack ofpiezo-electric elements in the piezo-electric power source); disposing apressing device on or over the piezo-electric power source (e.g., suchthat the pressing device obscures (e.g., contacts) the piezo-electricpower source); pressing the piezo-electric power source with thepressing device and removing the pressing device [e.g., such that thepiezo-electric power source is visible (e.g., is not in contact with thepressing device)]; waiting for a temporal delay of no less than onetenth of a second (e.g., no less than one quarter of a second, no lessthan one half of a second, or no less than one second) (e.g., and nomore than one minute); and receiving (e.g., observing) light output fromthe output device after the temporal delay.

In some aspects, the present disclosure provides a method of operating apiezo-electric device for converting mechanical pressure into electricalpower, comprising: providing the piezo-electric device (e.g., disposedon a security or value document), wherein the piezo-electric devicecomprises: a piezo-electric power source, a control circuit electricallyconnected to the piezo-electric power source, and an output deviceelectrically connected and responsive to the control circuit to outputenergy, wherein the control circuit controls the output device to outputenergy for a temporal output duration and the output duration istemporally delayed from the press duration by at least one msec, whereinthe press duration is a duration during which mechanical pressure isapplied to the piezo-electric power source (e.g., a stack ofpiezo-electric elements in the piezo-electric power source);transferring mechanical pressure from a pressing device into thepiezo-electric power source of the piezo-electric device, wherein lightis output from the output device after a temporal delay of no less thanone tenth of a second (e.g., no less than one quarter of a second, noless than one half of a second, or no less than one second) (e.g., andno more than one minute).

In some aspects, the present disclosure provides A method of disposingone or more micro-modules on or in a support substrate to provide alight-emitting module structure, comprising: providing a micro-modulesource wafer comprising one or more individual (e.g., separate andindependent) micro-modules, each of the one or more individualmicro-modules comprising: a rigid module substrate, an inorganiclight-emitting diode, a power source, and a control circuit, wherein theinorganic light-emitting diode, the power source, and the controlcircuit are each disposed on or in the module substrate and electricallyconnected such that the control circuit receives power from the powersource to control the inorganic light-emitting diode to emit light; andif the support substrate comprises a light conductor (e.g., disposed ata surface thereof), disposing the one or more micro-modules from themicro-module source wafer onto the support substrate, or else disposing(i) the one or more micro-modules on the support substrate and (ii) alight conductor on at least one of the support substrate and themicro-module, such that the light conductor is disposed in alignmentwith the inorganic light-emitting diode such that the inorganiclight-emitting diode emits light into the light conductor and the lightconductor conducts the light beyond the micro-module to emit the lightfrom the light-emitting module structure.

In certain embodiments, the micro-module source wafer comprises one ormore sacrificial portions, each sacrificial portion is disposed betweenanchor portions of the micro-module source wafer, and each micro-moduleis disposed completely over a sacrificial portion of the one or moresacrificial portions, and the method comprises: disposing one or moremicro-modules from the micro-module source wafer onto the supportsubstrate by micro-transfer printing the one or more micro-modules fromthe micro-module source wafer to the support substrate. In certainembodiments, the method comprises providing one or more inorganiclight-emitting diode (iLED) source wafers comprising one or moresacrificial portions, each sacrificial portion disposed between anchorportions of the iLED source wafer, and each iLED is disposed completelyover a sacrificial portion of the one or more sacrificial portions; anddisposing one or more iLEDs from the one or more iLED source wafers ontothe module substrate by micro-transfer printing the one or more iLEDsfrom the iLED source wafer to the module substrate.

In certain embodiments, the support substrate is at least a portion of asecurity or value document (e.g., is a portion of a security or valuedocument) or a layer on or in a security or value document. In certainembodiments, the method comprises disposing the support substrate ontoor into a document substrate that is at least a portion of a security orvalue document (e.g., a portion of a security or value document) or alayer on or in a security or value document. In certain embodiments, themethod comprises: adhering the one or more micro-modules from themicro-module source wafer to the document substrate; and removing thesupport substrate. In certain embodiments, the method comprises:providing a sealing or encapsulation layer over the one or moremicro-modules from the micro-module source wafer on the documentsubstrate.

In certain embodiments, the method comprises: disposing the one or moremicro-modules from the micro-module source wafer on a polymer carrier(e.g., prior to disposing the one or more micro-modules on the supportsubstrate); and disposing the polymer carrier on or over the supportsubstrate (e.g., wherein the one or more micro-modules are disposedbetween the polymer carrier and the support substrate). In certainembodiments, the method comprises: adhering the one or moremicro-modules from the micro-module source wafer to the supportsubstrate; and removing the polymer carrier.

In certain embodiments, the method comprises providing a sealing orencapsulation layer over the one or more micro-modules from themicro-module source wafer. In certain embodiments, the method comprisesproviding a sealing or encapsulation layer over the support substrateand the one or more micro-modules from the micro-module source waferdisposed on the support substrate.

In certain embodiments, the power source is a piezo-electric powersource comprising a plurality of piezo-electric elements. In certainembodiments, the method comprises disposing one or more piezo-electricelements onto or over a piezo-electric element to form a stack ofpiezo-electric elements. In certain embodiments, the method comprises:disposing each of the plurality of piezo-electric elements onto or overthe module substrate; and electrically connecting the plurality ofpiezo-electric elements. In certain embodiments, disposing the one ormore piezo-electric elements onto or over the piezo-electric element toform the stack comprises micro-transfer printing one or morepiezo-electric elements from a piezo-electric element source wafer ontothe piezo-electric element.

In certain embodiments, the piezo-electric element is disposed on themodule substrate. In certain embodiments, the piezo-electric element isdisposed on the module substrate by micro-transfer printing thepiezo-electric element from a piezo-electric element source wafer ontothe module substrate.

In certain embodiments, the method comprises: disposing each of one ormore electrical conductors over a piezo-electric element of theplurality of piezo-electric elements; and disposing a furtherpiezo-electric element of the plurality of piezo-electric elements ontoor over each electrical conductor. In certain embodiments, the methodcomprises: heating the one or more electrical conductors; and cooling(e.g., subsequently) the one or more electrical conductors to adhere thepiezo-electric element to the further piezo-electric element. In certainembodiments, the method comprises: heating all of the one or moreelectrical conductors simultaneously for a period of time; and cooling(e.g., subsequently) all of the one or more electrical conductorssimultaneously for a second period of time. Certain embodiments providemethods for making a light-emitting module structure that has a reducedsize and cost and integrating the light-emitting module structure into adocument substrate. The light-emitting module structure resistsenvironmental and mechanical damage.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other objects, aspects, features, and advantages ofthe present disclosure will become more apparent and better understoodby referring to the following description taken in conjunction with theaccompanying drawings, in which:

FIGS. 1A and 1B are cross sections of module structures according toillustrative embodiments of the present disclosure;

FIGS. 2A-2C are cross sections of module structures according toillustrative embodiments of the present disclosure;

FIGS. 3-6 are cross sections of module structures according toillustrative embodiments of the present disclosure;

FIGS. 7 and 8 are plan views of module structures according toillustrative embodiments of the present disclosure;

FIGS. 9A-9C are plan views of piezo-electric elements according toillustrative embodiments of the present disclosure;

FIGS. 10-11 are cross sections of piezo-electric elements and structureswith exploded views according to illustrative embodiments of the presentdisclosure;

FIGS. 12A and 12B are each a top and bottom view of a bank noteaccording to illustrative embodiments of the present disclosure;

FIGS. 13-16 are flow diagrams according to illustrative methods of thepresent disclosure;

FIG. 17 is a circuit schematic of a module structure according toillustrative embodiments of the present disclosure; and

FIGS. 18 and 19 illustrate the assembly and use of a bank note in a planview and perspective, respectively, in accordance with illustrativeembodiments of the present disclosure.

The features and advantages of the present disclosure will become moreapparent from the detailed description set forth below when taken inconjunction with the drawings, in which like reference charactersidentify corresponding elements throughout. In the drawings, likereference numbers generally indicate identical, functionally similar,and/or structurally similar elements. The figures are not necessarilydrawn to scale.

DETAILED DESCRIPTION OF CERTAIN EMBODIMENTS

The present disclosure provides, inter alia, structures and methods forincorporating and providing power to light-emitting elements in or on asupport substrate. The light-emitting elements are disposed on a rigidmodule substrate in a micro-module. A light conductor conducts lightfrom the light-emitting elements to a location on the support substrateremote from the micro-module. Such structures in value or securitydocuments can provide anti-counterfeiting features and documentvalidation to users of the document.

Referring to FIGS. 1A, 1B, 2A, 2B and 3-6 , in various illustrativeembodiments, a light-emitting module structure 99 comprises a supportsubstrate 10 and a micro-module 20 disposed on or in the supportsubstrate 10. The micro-module 20 extends over only a portion of thesupport substrate 10 so that the micro-module 20 covers only a portionof the support substrate 10 and does not cover the entire supportsubstrate 10. The support substrate 10 can be a flexible substrate, forexample a polymer or paper substrate.

The micro-module 20 can comprise a rigid module substrate 28, aninorganic light-emitting diode (iLED) 50, a power source 22, and acontrol circuit 24. (For clarity, the control circuit 24 and powersource 22 are not separately illustrated in FIGS. 3-6 .) In someembodiments, the module substrate 28 is more rigid than the supportsubstrate 10 and the support substrate 10 is more flexible than themodule substrate 28. The inorganic light-emitting diode 50, the powersource 22, and the control circuit 24 are disposed on or in the modulesubstrate 28 and the control circuit 24 receives power from the powersource 22 through electrical connections 26 to control the inorganiclight-emitting diode 50 to emit light 60.

The light-emitting module structure 99 comprises a light conductor 30disposed on or in the support substrate 10 and in alignment with themicro-module 20 so that the inorganic light-emitting diode 50 isdisposed to emit light 60 into the light conductor 30. In someembodiments, the light conductor 30 extends over only a portion of thesupport substrate 10. The light conductor 30 can cover the entiremicro-module 20 or only a portion of the micro-module 20. The lightconductor 30 conducts the light 60 beyond or away from the micro-module20 to emit the light 60 from the light conductor 30 or support substrate10 at light-emitting locations 12 remote from the micro-module 20. Light60 can be emitted from the light-emitting module structure 99, forexample, at the locations of diffusers, light-leaking structures,optical gaps (openings) in the light conductor 30, or at the ends,distal ends, or extremities of the light conductor 30 at the furthestextent of the light conductors 30 away from the micro-module 20. Thelight-emitting locations 12 can be located beyond an extent of themicro-module 20. Light 60 can be emitted into optical structures, suchas diffractive gratings or holograms.

The light conductor 30 can be a waveguide or a light-pipe and cancomprise a light-transmissive layer 32 disposed between reflectivelayers 40 and 42 (also called reflectors, 40, 42) or alight-transmissive cylinder coated or surrounded by a cladding orhigher-index structure or layer (not shown). Light-transmissive ortransparent means at least partially transparent or light-transmissiveto visible light, for example at least 30%, at least 50%, at least 70%,at least 80% or at least 90% transmissive to visible light. In someembodiments, the light is infrared or ultraviolet electromagneticradiation. Thus, in some embodiments, the light conductor 30 comprises areflector 40, 42 (e.g., reflective layers 40, 42) and a transparentlight-transmissive layer 32 adjacent to the reflector in a directionorthogonal to the support substrate 10 or disposed between tworeflectors 40, 42.

As shown in FIGS. 1A, 1B, 2A, 2B, the transparent, light-transmissivelayer 32 and the reflectors 40, 42 can be disposed in differentlocations. In some embodiments, the reflector 40 is disposed on thesupport substrate 10 between the support substrate 10 and themicro-module 20, the reflector 40, 42 is disposed on the supportsubstrate 10 so that the support substrate 10 is between the reflector40 and the micro-module 20, or the micro-module 20 is disposed betweenthe support substrate 10 and the reflector 40.

Referring to FIGS. 1A and 1B, the reflector 40 is disposed on a side ofthe support substrate 10 opposite the micro-module 20 and the reflector42 is disposed over the micro-module 20 and opposite the surface of thesupport substrate 10 on which the micro-module 20 is disposed. Thelight-transmissive layer 32 is disposed between the reflectors 40, 42.In FIG. 1A, the reflector 42 of the light conductor 30 extends beyondthe micro-module 20 and over only a portion of the support substrate 10but does not extend over the entire support substrate 10, so that light60 can escape and be emitted from the light-emitting module structure 99through light-emission locations 12. The reflector 40 can, but need notnecessarily, extend over the entire surface of the support substrate 10.As shown in FIG. 1A, light-emitting locations 12 are disposed on thesurface of the support substrate 10 on which the micro-module 20 isdisposed to emit light 60 from the light conductor 30 from the side ofthe light-emitting module structure 99 on which the micro-module 20 isdisposed.

In FIG. 1B, the reflector 40 of the light conductor 30 extends beyondthe micro-module 20 and over only a portion of the support substrate 10but does not extend over the entire support substrate 10, so that light60 can escape and be emitted from the light-emitting module structure99. The reflector 42 can, but need not necessarily, extend over theentire surface of the support substrate 10. As shown in FIGS. 1B and 1 ncontrast to the structure of FIG. 1A, light-emitting locations 12 aredisposed on the surface of the support substrate 10 opposite the surfaceon which the micro-module 20 is disposed to emit light 60 from the lightconductor 30 from the side of the light-emitting module structure 99opposite the side on which the micro-module 20 is disposed. In someembodiments, neither of the reflectors 40, 42 extends entirely over thesupport substrate 10 and light 60 is emitted from both sides of thelight-emitting module structure 99 or support substrate 10. A reflector40, 42 that comprises a light-emitting location 12 extends over only aportion of the support substrate 10 and does not extend over the entiresupport substrate 10.

Referring to FIGS. 2A and 2B, the reflector 40 is disposed on the sameside of the support substrate 10 as that on which the micro-module 20 isdisposed. The reflector 42 is disposed over the micro-module 20 and asurface of the light-transmissive layer 32. The light-transmissive layer32 is disposed between the reflectors 40, 42. In FIG. 2A, the reflector42 of the light conductor 30 extends beyond the micro-module 20 and overonly a portion of the support substrate 10 but does not extend over theentire support substrate 10, so that light 60 can escape and be emittedfrom the light-emitting module structure 99 through light-emissionlocations 12. The reflector 40 can, but need not necessarily, extendover the entire surface of the support substrate 10. As shown in FIG.2A, light-emitting locations 12 are disposed on the surface of thelight-transmissive layer 32 to emit light 60 from the light conductor 30from the side of the light-emitting module structure 99 on which themicro-module 20 is disposed. In FIG. 2B, the reflector 40 of the lightconductor 30 extends beyond the micro-module 20 and over only a portionof the support substrate 10 but does not extend over the entire supportsubstrate 10, so that light 60 can escape and be emitted from thelight-emitting module structure 99 at light-emitting locations 12. Thereflector 42 can, but need not necessarily, extend over the entiresurface of the support substrate 10. As shown in FIG. 2B and in contrastto the structure of FIG. 2A, light-emitting locations 12 are disposed onthe same surface of the support substrate 10 on which the micro-module20 is disposed to emit light 60 from the light conductor 30 from theside of the light-emitting module structure 99 opposite the side onwhich the micro-module 20 is disposed. In some embodiments, neither ofthe reflectors 40, 42 extends entirely over the support substrate 10 andlight 60 is emitted from both sides of the light-emitting modulestructure 99. A reflector 40, 42 that comprises a light-emittinglocation 12 extends over only a portion of the support substrate 10 anddoes not extend over the entire support substrate 10.

Referring to FIG. 2C, a third reflector/reflective layer 46 can beprovided so that reflectors 40, 46 are disposed on both sides of thesupport substrate 10. Light 60 can travel through both thelight-transmissive layer 32 between the reflectors 40, 42 and throughthe support substrate 10, so that at least portions of the supportsubstrate 10 are also a part of the light-transmissive layer 32 and thelight conductor 30. Light-emitting locations 12 can be disposed oneither or both sides of the support substrate 10 to allow light toescape from the light-emitting module structure 99. Thus, either, butnot both, of the reflectors 40, 46 can extend over the entire surface ofthe support substrate 10 on which they are respectively disposed, or, asshown, neither reflector 40, 46 extends over an entire support substrate10 surface.

Referring to FIGS. 3-6 , the micro-module 20 and iLED 50 can be orientedin different ways with respect to the support substrate 10. As shown inFIGS. 3 and 4 , the iLED 50 is a bottom emitter that primarily emitslight 60 through the module substrate 28 (which must be at leastpartially transparent). In FIG. 3 , the module substrate 28 is disposedbetween the support substrate 10 and the iLED 50 primarily emits light60 toward the reflector 40 and through the module substrate 28. In FIG.4 , the iLED 50 is disposed between the support substrate 10 and themodule substrate 28 and primarily emits light 60 through the modulesubstrate 28 toward the reflector 42. As shown in FIG. 5 , the iLED 50is a top emitter that primarily emits light 60 away from the modulesubstrate 28 (which can be opaque or reflective). In FIG. 5 , the iLED50 is disposed between the support substrate 10 and the module substrate28 and the iLED 50 primarily emits light 60 toward the reflector 40 andaway from the module substrate 28. In FIG. 6 , the module substrate 28is disposed between the support substrate 10 and the iLED 50 emits light60 both away from and through the modules substrate 28 (the iLED 50 isboth a top emitter and a bottom emitter). Thus, the iLED 50 emits light60 toward the reflector 42 and through the module substrate 28 towardthe reflector 40. In some embodiments (not shown), the iLED 50 of FIG. 6is a top emitter only and primarily emits light 60 toward the reflector42. In FIGS. 3 and 4 , the light-emitting locations 12 are disposed onthe same side of the support substrate 10 as that on which themicro-modules 20 are disposed (as in FIGS. 1A and 2A). However, thelight-emitting locations 12 could also be disposed on the opposite sideof the support substrate 10 as that on which the micro-modules 20 aredisposed. Similarly, in FIGS. 5 and 6 , the light-emitting locations 12are disposed on the opposite side of the support substrate 10 as that onwhich the micro-modules 20 are disposed (as in FIGS. 1B and 2B).However, the light-emitting locations 12 could also be disposed on thesame side of the support substrate 10 as that on which the micro-modules20 are disposed. In some embodiments, the light-emitting locations aredisposed on both sides of the support substrate 10.

FIGS. 1-6 illustrate a light conductor 30 in cross section. FIG. 7illustrates an embodiment showing a circular light conductor 30 in planview with a light-emitting location 12 disposed in a ring around thecircular light conductor 30, for example a diffuser, diffractivegrating, hologram, or other optical structure. In some embodiments, thelight conductor 30 can any of a variety of shapes, including rectangularor square, or an arbitrary shape with any combination of curves orstraight lines, for example like a cross section of an amoeba or anysimple closed curve. (In FIG. 7 , the micro-module 20 and iLED 50 areillustrated for clarity but are disposed between the reflector 42 andthe support substrate 10 and not visible in a top view.)

Referring to FIG. 8 , in some embodiments, the light conductor 30comprises one or more light pipes 44, for example a fiber opticstructure with a cladding or a reflective layer around the outside ofthe fiber. The light pipe 44 is disposed to receive light 60 from theiLED 50 and transmit or conduct the light 60 away from the micro-module20 to a light-emitting location 12. Light 60 is emitted from the lightemitting location 12 at the distal end of the light pipe 44, with orwithout the assistance of a diffuser or other optical structure.Multiple light pipes 44 can comprise the light conductor 30 thattransmit light 60 to corresponding multiple light-emitting locations 12.

The control circuit 24 can be an integrated circuit formed separatelyfrom the module substrate 28 and disposed on the module substrate 28,for example by micro-transfer printing, as shown in FIG. 1A. In someembodiments, the module substrate 28 is a semiconductor substrate, forexample a silicon substrate, and the control circuit 24 is formed atleast partially in or on the module substrate 28, as shown in FIG. 1B.

In some embodiments, the power source 22 or the iLED 50, or both thepower source 22 and the iLED 50, can be an integrated structure formedseparately from the module substrate 28 and disposed on the modulesubstrate 28, for example by micro-transfer printing. Thus, the controlcircuit 24 can be a micro-transfer printed integrated circuit having acircuit substrate separate (e.g., distinct and independent) from themodule substrate 28 and support substrate 10. Similarly, the inorganiclight-emitting diode 50 can be a micro-transfer printed light emitterhaving an iLED substrate separate (e.g., distinct and independent) fromthe module substrate 28 and support substrate 10 and the power source 22can be a micro-transfer printed power source 22 having a power sourcesubstrate separate (e.g., distinct and independent) from the modulesubstrate 28 and support substrate 10. Each of the control circuit 24(when a separate integrated circuit), the iLED 50, and the power source22 can be provided over one or more sacrificial portions between anchorportions of a source wafer and connected to an anchor portion with atether. When micro-transfer printed, the tether connecting the controlcircuit 24, iLED 50, or power source 22 to the anchor portion of thesource wafer is fractured or separated leaving a tether portion 90attached to the printed component (FIG. 1A). The micro-module 20 canalso be provided over one or more sacrificial portions between anchorportions of a source wafer and connected to an anchor portion with atether, and micro-transfer printed to the support substrate 10 soleaving a fractured or separated tether 90 (FIG. 1A).

In some embodiments, the power source 22 comprises a battery, a solarcell, a piezo-electric structure, or an antenna. Referring to FIGS. 9A,9B, 9C, 10 and 11 , the power source 22 can be a piezo-electric device76 electrically connected to electrical connections 26 that generateselectrical power in response to mechanical pressure. The piezo-electricdevice 76 can be a piezo-electric capacitor or comprise elements thatare piezo-electric capacitors and can be disposed on the modulesubstrate 28 or in general on any suitable substrate (e.g., supportsubstrate 10). Referring to FIG. 9A, the piezo-electric device 76 can bea single, monolithic piezo-electric element 70 disposed on the modulesubstrate 28. As shown in FIG. 9B, the piezo-electric device 76comprises multiple piezo-electric elements 70 electrically connected inparallel and distributed and spatially separated over a portion of themodule substrate 28. As shown in FIG. 9C, the piezo-electric device 76comprises multiple piezo-electric elements 70 electrically connected inserial and distributed over a portion of the module substrate 28.Referring to FIG. 10 , multiple piezo-electric elements 70 are disposedin a stack 74, for example a vertical stack disposed orthogonally to themodule substrate 28 or support substrate 10 (shown in FIG. 1A). Theindividual piezo-electric elements 70 can be micro-transfer printed ontop of each other and can each comprise a fractured or separated tether90 (not shown in FIG. 10 or 11 ). In some embodiments, the multiplepiezo-electric elements 70 of FIGS. 9B and 9C are stacks 74 of multiplepiezo-electric elements 70 where the piezo-electric elements 70 in eachstack 74 are serially connected and the stacks 74 are electricallyconnected in parallel (FIG. 9B) or in serial (FIG. 9C). As shown inFIGS. 9B and 9C for individual piezo-electric elements 70, each stack 74of the plurality of stacks of piezo-electric elements 74 is spatiallyseparated from every other stack of piezo-electric elements 74.

A schematic diagram of embodiments of the light-emitting modulestructure 99 is shown in FIG. 17 . As shown in FIG. 17 , a micro-module20 is disposed on a support substrate 10. FIG. 17 is not drawn to scale;in practice, the micro-module 20 is much smaller than the supportsubstrate 10, for example the micro-module 20 can have an area of tenthousand square microns and the support substrate 10 can have an area ofone hundred square centimeters. The micro-module 20 comprises a modulesubstrate 28 on which is disposed a power source 22, control circuit 24,and iLEDs 50 electrically connected with electrical connections 26. Thepower source 22 can, for example, comprise an array of piezo-electricelements 70 electrically connected to the control circuit 24 withelectrical connections 26 on the module substrate 28. The controlcircuit 24, in turn controls the light 60 output from the iLEDs 50. Forclarity of illustration, the light conductor 30 is omitted from FIG. 17.

Referring to the flow diagram of FIG. 16 , in step 200 thepiezo-electric elements 70 can be provided on or in a piezo-electricelement source wafer from which piezo-electric elements 70 can bemicro-transfer printed. The stack 74 of piezo-electric elements 70 can,itself, be micro-transfer printed. Thus, in some embodiments, a firstpiezo-electric element 70 is micro-transfer printed onto a power-sourcesubstrate such as a module substrate 28 in step 210, for example on anelectrical contact pad that is part of an electrical connection 26 onthe module substrate 28. Subsequent piezo-electric elements 70 can bemicro-transfer printed onto the first and subsequent piezo-electricelements 70 in step 220. In some embodiments, a piezo-electric elementsource wafer includes a first micro-transfer printable piezo-electricelement 70 (step 210). Subsequent piezo-electric elements 70 aremicro-transfer printed onto the first piezo-electric element 70 to forma stack 74 of piezo-electric elements 70 (step 220). The stack 74 ofpiezo-electric elements 70 can then be micro-transfer printed orotherwise transferred from the source wafer, for example onto the modulesubstrate 28 (step 260, shown with dashes to indicate an optional step).Thus, according to some embodiments, a method of making a piezo-electricpower source 22 comprises providing one or more element wafers, eachelement wafer comprising one or more piezo-electric elements 70, eachpiezo-electric element 70 disposed over a sacrificial portion separatedby anchor portions of the element wafer (step 200), providing apower-source substrate (step 210) such as a module substrate 28 orpower-source wafer that has a piezo-electric element 70 already disposedthereon (for example, either by micro-transfer printing a firstpiezo-electric element 70 thereon or forming the first piezo-electricelement 70 thereon), and releasing and micro-transfer printing one ormore piezo-electric elements 70 from the one or more element wafers ontoor over a piezo-electric element 70 on the power-source substrate toform a serially connected stack 74 of piezo-electric elements 70.Optionally, the stack 74 can be transferred to a power-source substrate,for example a module substrate 28, by micro-transfer printing or othertransfer methods if the stack 74 is not formed directly on thepower-source substrate (step 260).

As shown in FIG. 11 , an electrical conductor 72 can be disposed betweenthe individual piezo-electric elements 70 in the stack 74 (step 230 inFIG. 16 ). The electrical conductors 72 can be adhesive and can melt ata relatively low temperature (step 240). When cooled in step 250, theelectrical conductors 72 can firmly adhere the individual piezo-electricelements 70 in the stack 74. The electrical conductors 72 can be, forexample, a solder or solder-like material and can be deposited, forexample, by evaporation or coating and patterned, as necessary, byphotolithographic patterning or other methods. Thus, in methods inaccordance with some embodiments, one or more piezo-electric elements 70can be provided to comprise the power source 22. One or morepiezo-electric elements 70 can be disposed onto or over a piezo-electricelement 70. Piezo-electric elements 70 can be disposed in a stack 74 ofpiezo-electric elements 70, for example by micro-transfer printing apiezo-electric element 70 from a piezo-electric element source waferonto another piezo-electric element 70. Each of the one or morepiezo-electric elements 70 or stacks 74 of piezo-electric elements 70can be disposed onto or over the module substrate 28 and electricallyconnected, for example with electrical connections 26. Each of one ormore electrical conductors 72 is disposed over a piezo-electric element70 and another piezo-electric element 70 is disposed onto or over eachelectrical conductor 72. The electrical conductor 72 can be heated andcooled to adhere the piezo-electric element 70 to the otherpiezo-electric element 70. All of the electrical conductors 72 can beheated or cooled in a common step at the same time.

By providing a stack 74 of piezo-electric elements 70, a larger, morepowerful piezo-electric structure and power source 22 can be provided.Assembling large piezo-electric structures on small substrates can bedifficult. By micro-transfer printing the piezo-electric elements 70, alarger piezo-electric structure can be made in a smaller space. Thus, insome embodiments the piezo-electric elements 70 are less than or equalto 500 microns thick, 200 microns thick, 100 microns thick, 50 micronsthick, 20 microns thick, 10 microns thick, or 5 microns thick and thestack 74 of piezo-electric elements 70 is greater than or equal to 100microns thick, 500 microns thick, one mm thick, two mm thick, four mmthick, five mm thick, or 10 mm thick. The stack 74 of piezo-electricelements 70 can comprise two, three, four, five, ten, twenty, fifty, orone hundred piezo-electric elements 70, or more (e.g., at least three,at least four, at least five, at least 10, at least 20, at least 50, orat least one hundred piezo-electric elements) and the stack 74 can havean area in a plane orthogonal to the piezo-electric elements 70 stack 74(e.g., in the stack direction, a vertical direction with respect to asurface of the module substrate 28 or support substrate 10) of less thanor equal to 100 square mm, 25 square mm, one square mm, 250,000 squaremicrons, 40,000 square microns, 10,000 square microns, 2,500 squaremicrons, 1,000 square microns, 500 square microns, or 100 squaremicrons. A smaller area reduces the size of the micro-module 20 andthereby increases the flexibility of the support substrate 10.

In the micro-module 20, the power source 22, control circuit 24, andiLED 50 can be electrically connected by electrical connections 26 atleast partially on the module substrate 28 so that, responsive to powersupplied from the power source 22, the control circuit 24 controls theiLED 50 to emit light 60 into the light conductor 30. In someembodiments, the control circuit 24 is electrically connected throughelectrical connections 26 to a power source 22 comprising apiezo-electric device, for example individual piezo-electric elements70, multiple piezo-electric elements 70, or stacks 74 of piezo-electricelements 70.

The control circuit 24 can store power generated by or received from thepower source 22 and use the stored power to control the iLED 50 for aperiod of time longer than the period of time for which the power source22 is providing power. For example, the control circuit 24 can compriseone or more capacitors. Moreover, the control circuit 24 can incorporatepower converters for converting power from the power source 22 to avoltage and current suitable for the control circuit 24 and iLEDs 50.Thus, according to embodiments, the control circuit 24 can convert theelectrical power produced by the power source 22 from one voltage,current, or temporal duration to another different voltage, current, ortemporal duration.

According to some embodiments, a temporal duration for applyingmechanical pressure to the piezo-electric elements 70 or stack 74 (e.g.,by a pressing device) is a press duration, and the control circuit 24outputs energy for a temporal output duration. The output duration canbe less than the press duration. The output duration can be greater thanthe press duration. In some embodiments, an output duration is no lessthan one msec (e.g., no less than ten msecs, no less than 50 msecs, noless than 100 msecs, no less than 500 msecs, or no less than one second)(e.g., and no more than one minute). In some embodiments, an outputduration can be temporally delayed from a press duration by at least onemsec (e.g., at least ten msecs, at least 50 msecs, at least 100 msecs,at least 500 msecs, or at least one second) (e.g., and no more than oneminute). By delaying an output, an observer who obscures a portion of asupport substrate 10, for example with pressing device (e.g., a finger),in order to press a piezo-electric power source 22, has time to removethe pressing device so that the pressing device does not obscure light60 output by a light-emitting module structure 99. An output durationcan be selected to be long enough to be readily visible but short enoughto reduce the amount of power used. A pressing device can be a finger oran object (e.g., a rigid object) sized and shaped to press apiezo-electric power source 22, for example.

The emitted light 60 travels (is conducted or transmitted) through thelight conductor 30 and then emitted from the light-emitting modulestructure 99 at light-emitting locations 12, for example throughopenings, optical gaps, diffusers, or other light-leaking structures, sothat an observer can observe the emitted light 60. Certain embodimentshave the advantage that all of the electrical connections 26 aredisposed only on the rigid module substrate 28 so that when the supportsubstrate 10 is flexed, the rigid module substrate 28 resists theflexing and preserves the electrical connections 26 electricallyconnected to the iLED 50, the power source 22, and the control circuit24. The light conductor 30 and the alignment of the light conductor 30with the iLED 50 are less susceptible to damage from mechanicalmanipulation and the light conductor 30 can be more flexible than themicro-module 20. Because the iLED 50, the power source 22, and thecontrol circuit 24 can be micro-transfer printed, as can themicro-module 20 itself, the micro-module 20 can be very small, forexample having an area less than or equal to 250,000 square microns,40,000 square microns, 10,000 square microns, 2,500 square microns,1,000 square microns, 500 square microns, or 100 square microns. Becausethe micro-module 20 can be very small, the micro-module 20 is subject toreduced mechanical and environmental stress, for example when thesupport substrate 10 is folded or otherwise flexed. However, the light60 emitted by the ILED 50 can be distributed over a wider area than themicro-module 20 and is therefore more readily visible because theemitted light 60 is transmitted through the light conductor 30. Becausethe light conductor 30 is more mechanically robust than the electricalconnections 26, according to some embodiments, flexing the supportsubstrate 10 does not necessarily prevent the emitted light 60 fromentering and traveling through the light conductor 30 to the lightdiffuser or light leak at a light-emitting location 12. Thus, certainembodiments provide distributed light emission (over the supportsubstrate 10) with only local electrical connections 26 (over the modulesubstrate 28). This distributed light emission is more readily visibleto an observer, particularly if the observer obscures a portion of thesupport substrate 10, for example with a finger.

Referring to FIG. 12A, in some embodiments, the support substrate 10 isa document substrate 80, for example a security or value document, or asubstrate or layer in a security or value document, such as a banknoteon which the micro-module 20 is disposed to make a light-emitting modulestructure 99 in accordance with some embodiments of the presentdisclosure. Referring to FIG. 12B and FIG. 18 , in some embodiments, thesupport substrate 10 is a security strip comprising one or moremicro-modules 20 that are disposed or embedded on or in, or woven into,or laminated to a document substrate 80, for example a security or valuedocument, or a substrate or layer in a security or value document, suchas a banknote to make the light-emitting module structure 99.

The support substrate 10 (or document substrate 80) can comprise opticalstructures such as diffusers, holograms, diffractive elements, lenses orother optical elements. The optical structures can be visible to anunaided human observer. In some embodiments, the optical structures areonly visible with the assistance of equipment, such as microscopes orinfrared or UV light sources or viewers. The iLED 50 can emit light 60into the light conductor 30 and the light conductor 30 can transmit theemitted light 60 into the optical structure, for example to illuminatethem to an observer, as shown in FIG. 19 . In FIG. 19 , a pressingdevice (in this example, a finger) presses on and obscures themicro-module 20 and the light conductor 30 (FIG. 1A) conducts the light60 to light-emitting locations 12 away from the micro-module 20 that arenot obscured by the finger.

According to some embodiments, light-emitting module structures 99 suchas those of FIG. 18 , are constructed using methods illustrated in theflow diagrams of FIGS. 13-15 . Referring to FIG. 13 , a supportsubstrate 10, such as a banknote or other value or security documenthaving a document substrate 80 (equivalent to the support substrate 10in this embodiment), is provided in step 100. Source wafers for one ormore of the elements comprising the micro-module 20 are provided in step110, for example source wafers having micro-transfer printablecomponents such as iLEDs 50, integrated control circuits 24, or powersources 22 and a micro-module source wafer or source substrate isprovided in step 120. The components are micro-transfer printed from thesource wafers (or transferred from other source materials) onto themodule substrate 28 or other source substrate of the micro-module sourcewafer in step 130. The module substrate 28 can be on a source waferitself from which it can be micro-transfer printed or the modulesubstrate 28 can be on another source substrate from which it can betransferred, for example using pick-and-place or surface-mount methods,tools, and materials. The micro-modules 20 can be processed to formelectrical connections 26 electrically connecting the components afterthe components are transferred or the electrical connections 26 can beformed prior to disposing the components on the module substrate 28.Once the micro-module 20 is completed, it is optionally sealed orencapsulated for protection (step 135) and then transferred, for exampleby micro-transfer printing or other transfer methods, such aspick-and-place or surface-mount assembly techniques, to the supportsubstrate 10 (step 140). The support substrate 10 can be sealed orcoated or otherwise processed to encapsulate or protect themicro-modules 20 in step 150, as necessary.

In some embodiments such as those illustrated in FIG. 13 , the supportsubstrate 10 can be a document substrate 80 of a value or securitydocument (e.g., a banknote or a component of a banknote such as asecurity strip as shown in FIG. 12A) or a component of a documentsubstrate 80 (e.g., a security strip or thread as shown in FIGS. 12B and18 ) that is subsequently disposed on a document substrate 80 (step160). As shown in FIG. 13 , the light conductor 30 can be disposed,applied, or formed in step 180 at any of a variety of steps in theprocess illustrated in FIG. 13 , for example on or over the micro-module20 and applied with the micro-module 20 to the support substrate 10,disposed on the support substrate 10 before the micro-module 20 isdisposed on the support substrate 10, or disposed on the supportsubstrate 10 after the micro-module 20 is disposed on the supportsubstrate 10, and generally before or after any sealing, coating orencapsulating step (ordered arbitrarily in FIG. 13 ). If the supportsubstrate 10 is a component in a document substrate 80 such as abanknote, the support substrate 10 can be applied, laminated, or woveninto the document substrate 80 (step 160).

Referring to FIG. 14 , an illustrative embodiment explicitlyincorporating a security strip or thread as the support substrate 10 areillustrated. Referring to FIG. 14 , a document substrate 80, such as abanknote or other value or security document having a document substrate80, is provided in step 107. Security strips (which can be supportsubstrates 10) are provided in step 105. Source wafers for one or moreof the elements comprising the micro-module 20 are provided in step 110,for example source wafers having micro-transfer printable componentssuch as iLEDs 50, integrated control circuit 24, or power sources 22 anda micro-module source wafer or source substrate is provided in step 120.The components are micro-transfer printed from the source wafers (ortransferred from other source materials) onto the module substrate 28 orother source substrate of the micro-module source wafer in step 130. Themodule substrate 28 can be on a source wafer itself from which it can bemicro-transfer printed or the module substrate 28 can be on anothersource substrate from which it can be transferred, for example usingpick-and-place or surface-mount methods, tools, and materials. Themicro-modules 20 can be processed to form electrical connections 26electrically connecting the components after the components aretransferred or the electrical connections 26 can be formed prior todisposing the components on the module substrate 28 (not shown in FIGS.13-15 , but can be considered to be a part of step 130). In someembodiments, the light conductor 30 can be provided (step 180) with themicro-module 20 before or after the components are transferred to themodule substrate 28.

Once the micro-module 20 is completed, it is optionally sealed orencapsulated to protect it (FIG. 13 , step 135) and then transferred,for example by micro-transfer printing or other transfer methods, suchas pick-and-place or surface-mount assembly techniques, to the securitystrip (support substrate 10, step 145, equivalent to step 140 in FIG. 13). The security strip (support substrate 10) can be sealed or coated orotherwise processed to encapsulate or protect the micro-modules 20, asnecessary (in step 150, shown in FIG. 13 ). In some embodiments, thelight conductor 30 can be disposed on the micro-module 20 before orafter the components are disposed on the micro-module substrate 28 (step180). Once the security strip (support substrate 10) is completed, it isoptionally sealed or encapsulated for protection (step 150, FIG. 13 )and then transferred, for example by lamination or weaving, to thedocument substrate 80 (step 160). The document substrate 80 can besealed or coated or otherwise processed to encapsulate or protect themicro-modules 20, as necessary. In some embodiments, the light conductor30 can be disposed on the document substrate 80 before or after thesecurity strip (support substrate 10) is disposed on the documentsubstrate 80 (step 180).

In some embodiments, the security strip (support substrate 10) comprisesa pressure-sensitive adhesive with a release liner and can be removed instep 170, e.g., by peeling, leaving the micro-module 20 and lightconductor 30 behind on the document substrate 80, to form a structuresimilar to that of FIG. 12A. In some embodiments, the security strip(support substrate 10) remains, as shown in FIG. 12B.

The use of an adhesive tape with a release liner can be applied moregenerally in some embodiments of the present disclosure. Referring toFIG. 15 , the component source wafers are provided in step 110 andmicro-module wafers in step 120. The components are micro-transferprinted from the component source wafers to the module substrates 28 ofthe micro-module wafers in step 130. A polymer carrier (e.g., anadhesive tape with a release liner) is provided in step 115 and themicro-modules 20 transferred to the polymer carrier (e.g., bymicro-transfer printing, pick-and-place methods, or surface-mounttechniques) in step 147. The polymer carrier is then applied to thesecurity strip (support substrate 10, or to a document substrate 80) instep 165, the micro-modules 20 are adhered to the security strip(support substrate 10), and the polymer carrier is removed in step 175.The security strip (support substrate 10) can then be integrated withthe document substrate 80 in step 160.

Thus, in some embodiments, a method of disposing one or moremicro-modules 20 on or in a support substrate 10 to provide alight-emitting module structure 99 comprises providing a micro-modulesource wafer comprising one or more individual (e.g., separate andindependent) micro-modules 20, each micro-module 20 comprising a rigidmodule substrate 28, one or more inorganic light-emitting diodes 50, apower source 22, and a control circuit 24. The inorganic light-emittingdiode 50, the power source 22, and the control circuit 24 are disposedon or in the module substrate 28 and the control circuit 24 receivespower from the power source 22 to control the one or more inorganiclight-emitting diodes 50 to emit light. If the support substrate 10comprises a light conductor 30, one or more of the micro-modules 20 aredisposed onto the support substrate 10, or else one or more of themicro-modules 20 are disposed onto the support substrate 10 and a lightconductor 30 is disposed on the support substrate 10 or the micro-module20, or both. The light conductor 30 is disposed in alignment with theone or more inorganic light-emitting diodes 50 so that the inorganiclight-emitting diodes 50 emit light 60 into the light conductor 30 andthe light conductor 30 conducts the light 60 beyond the micro-module 20to emit the light 60 from any one or all of the light conductor 30,light-emitting module structure 99, or support substrate 10.

In some embodiments, the micro-module source wafer comprises one or moresacrificial portions. Each sacrificial portion is disposed betweenanchor portions of the micro-module source wafer, and each micro-module20 is disposed completely over a sacrificial portion. One or more of themicro-modules 20 are disposed onto the support substrate 10 bymicro-transfer printing one or more micro-modules 20 from themicro-module source wafer to the support substrate 10. Similarly, one ormore inorganic light-emitting diode (iLED) source wafers comprise one ormore sacrificial portions. Each sacrificial portion is disposed betweenanchor portions of the iLED source wafer, and each iLED 50 is disposedcompletely over a sacrificial portion. One or more of the iLEDs 50 aredisposed onto the module substrate 28 by micro-transfer printing one ormore iLEDs 50 from the iLED source wafer to the module substrate 28.

In some embodiments, the support substrate 10 is at least a portion of asecurity or value document (e.g., is a security or value document) or alayer on or in a security or value document or document substrate 80. Insome embodiments, the support substrate 10 can be disposed onto or intoa document substrate 80 that is at least a portion of a security orvalue document (e.g., is a security or value document) or a layer on orin a security or value document.

In methods in accordance with some embodiments, micro-modules 20 areadhered to the document substrate 80 and the support substrate 10 isremoved. A polymer carrier can be provided and the micro-module 20disposed on the polymer carrier and the polymer carrier disposed on thesupport substrate 10. The micro-module 20 can be adhered to the supportsubstrate 10 and the polymer carrier removed or peeled from the supportsubstrate 10. A sealing or encapsulation layer can be provided over themicro-module 20, provided over the micro-module 20 on the supportsubstrate 10, provided over the polymer carrier, or provided over thedocument substrate 80.

The power source 22 can be a piezoelectric power source 22 or aphotovoltaic power source 22 and the control circuit 24 can convert thepower provided by the power source 22 to a form that is used by theiLEDs 50. The control circuit 24 can include power storage, for exampleusing capacitors such as thin-film capacitors with a high-K dielectricto provide power over a time period. The capacitors can be distributed,for example located among a plurality of piezo-electric elements 70.Output diodes can be used to isolate the power source 22 or iLEDs 50. Inone arrangement, the micro-modules 20 or light conductor 30 areindicated by visible markings on the support substrate 10 or documentsubstrate 80 or form visible markings on the support substrate 10 ordocument substrate 80.

In some embodiments, the power source 22 comprises a plurality ofelectrically connected but physically separated individual powercomponent, e.g., as piezo-electric elements 70. The piezo-electricelements 70 can be arranged in a 2-d array or a 1-d array and the powersource 22 operated by squeezing, waving, or sliding an object across thepower source 22. The power components can be a group of elements thatare operated at the same time with a single action, for example pressureapplied to all of the power components simultaneously (e.g., by apressing device). The power components, e.g., piezo-electric elements70, can be electrically arranged in series to achieve a desired voltageor in parallel to achieve a desired current or some combination ofseries and parallel to achieve the desired power characteristics.

The iLEDs 50 can be unpackaged micro-light-emitting diodes suitable formicro-transfer printing, for example made on a doped compoundsemiconductor wafer adapted to the manufacture of inorganiclight-emitting diodes 50. The iLEDs 50 can be bare die.

The control circuit 24 can also be an integrated circuit, for example asmall chiplet such as a bare die, suitable for micro-transfer printing.The control circuit 24 can be integrated into or on a semiconductorsubstrate such as a silicon substrate and can be provided as a bare die.The control circuit 24 can include digital circuits or logic (forexample CMOS circuits) and power circuits (for example for driving aniLED 50). The control circuit 24 can include information storagecircuits, a state machine, or a stored program machine to implement thedesired functionality of the light-emitting module structure 99. Thepower source 22 can be directly connected to the control circuit 24 (asshown in FIG. 17 ) or to the iLEDs 50, or both. In some embodiments, thepower source 22 can indirectly connect to the control circuit 24 or theiLEDs 50, or both through the electrical connections 26. The electricalconnections 26 can be any patterned electrically conductive element, forexample small wires, and can include power or circuit connection padsthat, when electrically connected to a power source 22 provides power tothe control circuit 24 and iLEDs 50 to enable them to function.

It can be desirable to fold or spindle a support substrate 10 in someembodiments without damaging the light-emitting module structure 99. Tofacilitate such manipulation without damage, in some embodiments, thepower source 22, iLED 50, and control circuit 24 are small, for examplehaving dimensions less than 50 microns, 20 microns, or ten microns, andthe micro-module 20 is also small, for example having dimensions lessthan 500 microns, 250 microns, 100 microns, 50 microns, or 20 microns.Although the module substrate 28 is relatively rigid, because it issmall and incorporated within a flexible and somewhat compliant supportsubstrate 10, the support substrate 10 can bend without breaking themicro-module 20 or light conductor 30.

In some embodiments, the iLEDs 50 and micro-module 20 are too small tobe readily visible with the unaided human eye. Furthermore, the iLEDs 50and control circuit 24 can be located in areas of the support substrate10 that include visible markings to further obscure the presence of theiLEDs 50, light conductor 30, and micro-module 20. The support substrate10 can be marked, for example by printing on a high-quality paper withink using intaglio printing. Similarly, the power source 22 or anarrangement of individual smaller power piezo-electric elements 70 canbe obscured by the visible markings. In one embodiment, the micro-module20 or light conductor 30 is marked with visible markings. For example,ink can be printed over the light conductor 30 or micro-module 20 or anyof its components to obscure them or otherwise make them a part of thevisible markings on the support substrate 10 (e.g., a banknote).

Since the micro-module 20 and any of its components, e.g., iLEDs 50,control circuit 24, electrical connections 26 (wires), power source 22,can each be very small, for example having a size in the micron range,they can be effectively invisible to the unaided human eye. For example,the one or more inorganic micro light-emitting diodes 50 or the controlcircuit 24 of the light-emitting module structure 99 can have a widthfrom 2 to 50 μm (e.g., 2 to 5 μm, 5 to 10 μm, 10 to 20 μm, or 20 to 50μm, a length from 2 to 50 μm (e.g., 2 to 5 μm, 5 to 10 μm, 10 to 20 μm,or 20 to 50 μm), and/or a height from 2 to 50 μm (e.g., 2 to 5 μm, 5 to10 μm, 10 to 20 μm, or 20 to 50 μm).

In some embodiments, the support substrate 10, security strips, orthreads can include a metalized or metallic ribbon or thread, forexample Mylar. The support substrate 10 can have one or more opticalstructures disposed in a pattern. The support substrate 10 can comprisepaper, such as cotton paper, plastic-coated paper, orplastic-impregnated paper. The polymer carrier can be a plastic,polymer, or resin sheet or substrate, for example having a thickness ofno more than 250 microns, no more than 100 microns, no more than 50microns, or no more than 20 microns or less.

The light conductor 30 can comprise waveguides, light pipes 44, oroptical fibers and can include optical structures include lenses,refractive, or diffractive optical elements, for example comprisingglass, plastic, or polymer materials, as well as more rigid materialssuch as silicon oxides or nitrides. The reflectors 40, 42, can beevaporated or laminated metal layers, for example aluminum, silver,gold, tin, or other reflective metals or metal alloys, or otherreflective materials. The light conductor 30 can be more flexible thanthe micro-modules 20 and less or equally flexible as the supportsubstrate 10 or document substrate 80.

In some embodiments, one or more light pipes 44 are located inassociation with the one or more inorganic light-emitting diodes 50 totransmit light 60 emitted by the inorganic light-emitting diodes 50through the light pipes 44 and emit the transmitted light 60 from theopposite end of the light pipe 44 at a light-emitting location 12 remotefrom the micro-module 20 and iLED 50. In some embodiments, the lightpipes 44 include portions that leak light 60 at desired locations, forexample by purposefully forming nicks, scratches, or other forms oflight diffusers in the light pipes 44 to allow light 60 to leak from thelight pipe 44. Thus, the arrangement of the light pipes 44 can alsocorrespond to a portion of the visible markings of the support substrate10 to highlight or otherwise indicate the portion of the visiblemarkings, form a graphic indicator, or form any one or all of a number,a letter, and a pictogram to indicate a value, a date, or a person.

The control circuit 24 can control the one or more inorganiclight-emitting diodes 50 to flash or sequentially flash individual iLEDs50, forming spatial, temporal, or temporal-spatial light patterns. Ifthe light-emitting module structure 99 comprises multiple iLEDs 50, theiLEDs 50 can emit different colors of light. For example, a redlight-emitting diode 50 can emit red light, a green light-emitting diode50 can emit green light, and a blue light-emitting diode 50 can emitblue light. The different inorganic light-emitting diodes 50 can bearranged spatially to form a display, a two-dimensional array, or agraphic element.

Components on a source wafer are released from the source wafer byetching away a sacrificial portion, leaving the components suspendedover the sacrificial portion and connected to an anchor portion by thetether. Components are micro-transfer printed from a source wafer ontothe module substrate 28 using a stamp to fracture the tethers connectingthe components to the source wafer leaving at least a tether portion 90on the components (shown in FIG. 1A).

A light-emitting module structure 99 in accordance with some embodimentscan be used by first receiving the light-emitting module structure 99,providing power to the control circuit 24 from the power source 22, forexample by mechanically pressing, squeezing, or stretching thepiezo-electric structure, exposing the solar cell to light, or providingelectromagnetic radiation to the antenna, and using the control circuit24 to cause the iLEDs 50 to emit light 60 into the light conductor 30and out of the light-emitting locations 12, and viewing the emittedlight. Mechanical manipulation can be done by hand, for example with oneor more fingers.

As shown in FIG. 19 , in accordance with some embodiments, alight-emitting module structure 99 having a piezoelectric power source22 can be pressed or squeezed, for example, by a finger, to providepower to iLEDs 50, causing the iLEDs 50 to emit light. Power is providedboth when pressing and releasing. It has been demonstrated that afingertip having a one square cm area can provide a force of 35N. Evenwith a smaller force of 10N, a piezoelectric power source 22 with atotal area of 0.06 cm² provides sufficient power to operate apiezoelectric according to some embodiments, including digital controlfor iLED 50 sequencing, for example flashing. With larger forces,functional light-emitting module structure 99 can have an area less than25,000 square microns.

U.S. patent application Ser. No. 14/743,981, filed Jun. 18, 2015,entitled “Micro Assembled Micro LED Displays and Lighting Elements”,incorporated herein by reference describes micro-transfer printingstructures and processes useful in certain embodiments of the presentdisclosure. For a discussion of micro-transfer printing techniques seealso U.S. Pat. Nos. 8,722,458, 7,622,367 and 8,506,867, each of which ishereby incorporated by reference in its entirety. Micro-transferprinting using compound micro assembly structures and methods can alsobe used in certain embodiments, particularly for micro-modules 20, andfor example as described in U.S. patent application Ser. No. 14/822,868,filed Aug. 10, 2015, entitled “Compound Micro-Assembly Strategies andDevices”, which is hereby incorporated by reference in its entirety.

As is understood by those skilled in the art, the terms “over”, “under”,“above”, “below”, “beneath”, and “on” are relative terms and can beinterchanged in reference to different orientations of the layers,elements, and substrates included in various embodiments of the presentdisclosure. For example, a first layer on a second layer in someembodiments means a first layer directly on and in contact with a secondlayer. In some embodiments, a first layer on a second layer can includeanother layer there between.

Throughout the description, where apparatus and systems are described ashaving, including, or comprising specific components, or where processesand methods are described as having, including, or comprising specificsteps, it is contemplated that, additionally, there are apparatus, andsystems of the disclosed technology that consist essentially of, orconsist of, the recited components, and that there are processes andmethods according to the disclosed technology that consist essentiallyof, or consist of, the recited processing steps.

It should be understood that the order of steps or order for performingcertain action is immaterial so long as the disclosed technology remainsoperable. Moreover, two or more steps or actions in some circumstancescan be conducted simultaneously. Certain embodiments have been describedin particular detail above, but it is understood that variations andmodifications can be effected within the spirit and scope of theinvention.

PARTS LIST

-   -   10 support substrate    -   12 light-emitting location    -   20 micro-module    -   22 power source    -   24 control circuit    -   26 electrical connections    -   28 module substrate    -   30 light conductor    -   32 light-transmissive layer/transparent layer    -   40 reflector/reflective layer    -   42 reflector/reflective layer    -   44 light pipe    -   46 reflector/reflective layer    -   50 inorganic light-emitting diode (iLED)    -   60 emitted light    -   70 piezo-electric element    -   72 electrical conductor    -   74 stack of piezo-electric elements    -   76 piezo-electric device    -   80 document substrate    -   90 tether portion/separated tether    -   99 light-emitting module structure    -   100 provide flexible substrate step    -   105 provide security strip step    -   107 provide document substrate step    -   110 provide source wafers step    -   115 provide polymer carrier step    -   120 provide micro-module wafer step    -   130 micro-transfer print components onto micro-module wafer step    -   135 optional seal/coat step    -   140 micro-transfer micro-modules onto support substrate step    -   145 micro-transfer print micro-module onto security strip step    -   147 micro-transfer print micro-module onto polymer carrier step    -   150 optional seal/coat step    -   160 dispose support substrate into document substrate step    -   165 laminate polymer carrier on security strip step    -   170 optional peel security strip step    -   175 peel polymer carrier step    -   180 optional dispose light conductor step    -   200 provide piezo-electric element source wafer    -   210 provide piezo-electric element on substrate step    -   220 micro-transfer print piezo-electric element from source        wafer onto piezo-electric    -   element on substrate step    -   230 dispose electrical conductor onto piezo-electric element        step    -   240 optional heat electrical conductors step    -   250 optional cool electrical conductors step    -   260 transfer power source to module substrate step

What is claimed is:
 1. A piezo-electric power source comprising: a stackof piezo-electric elements that are electrically connected in serial,wherein the piezo-electric elements of the stack are responsive tomechanical pressure to produce electrical power; and a control circuitelectrically connected to the stack of piezo-electric elements forconverting the electrical power from one temporal duration to anothertemporal duration and the control circuit is adapted to convert a pressduration that is a temporal duration that mechanical pressure is appliedto the stack of piezo-electric elements to an output duration duringwhich energy is output, wherein the control circuit controls the outputduration to be temporally delayed from the press duration by at leastone msec.
 2. The piezo-electric power source of claim 1, comprising anelectrical conductor disposed in the stack between at least two of thepiezo-electric elements.
 3. The piezo-electric power source of claim 1,wherein the piezo-electric elements are no more than 500 microns thick.4. The piezo-electric power source of claim 1, wherein the stack ofpiezo-electric elements has a thickness of at least 100 microns.
 5. Thepiezo-electric power source of claim 1, wherein the stack ofpiezo-electric elements comprises at least two piezo-electric elements.6. The piezo-electric power source of claim 1, wherein the stack ofpiezo-electric elements comprises at least three piezo-electricelements.
 7. The piezo-electric power source of claim 1, wherein thestack has an area in a plane orthogonal to the stack of piezo-electricelements.
 8. The piezo-electric power source of claim 1, comprising aplurality of stacks of piezo-electric elements, wherein the stacks ofpiezo-electric elements in the plurality of stacks of piezo-electricelements are electrically connected in parallel.
 9. The piezo-electricpower source of claim 1, comprising a plurality of stacks ofpiezo-electric elements wherein each stack of the plurality of stacks ofpiezo-electric elements is spatially separated from every other stack ofpiezo-electric elements.
 10. The piezo-electric power source of claim 1,wherein one or more of the piezo-electric elements of the stack ofpiezo-electric elements is a piezo-electric capacitor.
 11. Thepiezo-electric power source of claim 1, comprising a control circuit,electrically connected to the stack of piezo-electric elements, forstoring at least a portion of the electrical power.
 12. Thepiezo-electric power source of claim 1, wherein the output duration isgreater than or equal to one msec.
 13. The piezo-electric power sourceof claim 1, wherein the piezo-electric power source comprises a supportsubstrate and the stack of piezo-electric elements is disposed on thesupport substrate, or the piezo-electric power source comprises a modulesubstrate, and the stack of piezo-electric elements is disposed on themodule substrate.
 14. The piezo-electric power source of claim 1,comprising a plurality of stacks of piezo-electric elements, wherein thestacks of piezo-electric elements in the plurality of stacks ofpiezo-electric elements are electrically connected in parallel and eachstack of the plurality of stacks of piezo-electric elements is spatiallyseparated from every other stack of piezo-electric elements.
 15. Apiezo-electric power source comprising: a stack of piezo-electricelements that are electrically connected in serial, wherein thepiezo-electric elements of the stack are responsive to mechanicalpressure to produce electrical power; and a control circuit electricallyconnected to the stack of piezo-electric elements for converting theelectrical power from one temporal duration to another temporal durationand the control circuit is adapted to convert a press duration that is atemporal duration that mechanical pressure is applied to the stack ofpiezo-electric elements to an output duration during which energy isoutput, wherein the output duration is less than the press duration. 16.A piezo-electric power source comprising: a stack of piezo-electricelements that are electrically connected in serial, wherein thepiezo-electric elements of the stack are responsive to mechanicalpressure to produce electrical power; and a control circuit electricallyconnected to the stack of piezo-electric elements for converting theelectrical power from one temporal duration to another temporal durationand the control circuit is adapted to convert a press duration that is atemporal duration that mechanical pressure is applied to the stack ofpiezo-electric elements to an output duration during which energy isoutput, wherein the output duration is greater than the press duration.17. A piezo-electric power source comprising: a stack of piezo-electricelements that are electrically connected in serial, wherein thepiezo-electric elements of the stack are responsive to mechanicalpressure to produce electrical power; and a control circuit electricallyconnected to the stack of piezo-electric elements for converting theelectrical power from one temporal duration to another temporal durationand the control circuit is adapted to convert a press duration that is atemporal duration that mechanical pressure is applied to the stack ofpiezo-electric elements to an output duration during which energy isoutput, wherein the output duration is greater than or equal to onemsec.